Daily Aspirin therapy:
Aspirin interferes with your blood's clotting action.
It can prevent clots, which can form around vessels that are already narrowed from atherosclerosis. These clots can block blood flow to the heart and cause a heart attack.

Very low doses of aspirin --75 milligrams (mg), which is less than a standard baby aspirin -- can be effective. Your doctor will usually prescribe a daily dose anywhere from 81 mg -- the amount in a baby aspirin -- to 325 mg (a regular strength tablet).

A September 2015 report by Kaiser Permanente Research for the Agency for Healthcare Research and Quality of the Dept of Health and Human Services
"Aspirin Use to Prevent Cardiovascular Disease and
Colorectal Cancer: A Decision Analysis", says,
" Evidence indicates that aspirin is effective for the primary prevention of
cardiovascular disease (CVD) and colorectal cancer (CRC), but regular use also increases risk for gastrointestinal (GI) and cerebral hemorrhages.

They recommend aspirin therapy for adults aged 50-59 who are at high risk * for cardiovascular disease.